Abstract
Response of an elastic dam-foundation system to a horizontal impulse is analyzed by a FE-BE method in time domain. The method has proved to be effective not only in calculation of the response itself but also in getting many vibration modes of the system from the response. As eigen values pertaining to the system are complex, the present procedure based on the time domain analysis seems to be superior to the determinant search procedure applied to a frequency domain analysis. From a practical point of a view, the present analysis places a main focus on effects of an impedance ratio on vibration characteristics such as radiation damping, natural frequency and vibration mode shape. The vibration shape which is obtained in a complex form is plotted in terms of its real and imaginary parts, showing interaction between the dam and foundation.
